Latitudinal Limits Research Articles

Mangroves Response to Climate Change: A Review of Recent Findings on Mangrove Extension and Distribution.

Mangroves function as a natural coastline protection for erosion and inundation, providing important environmental services. Due to their geographical distribution at the continent-ocean interface, the mangrove habitat may suffer heavy impacts from global climate change, maximized by local human activities occurring in a given coastal region. This review analyzed the literature published over the last 25 years, on the documented response of mangroves to environmental change caused by global climate change, taking into consideration 104 case studies and predictive modeling, worldwide. Most studies appeared after the year 2000, as a response to the 1997 IPCC report. Although many reports showed that the world's mangrove area is decreasing due to direct anthropogenic pressure, several others, however, showed that in a variety of habitats mangroves are expanding as a response to global climate change. Worldwide, pole ward migration is extending the latitudinal limits of mangroves due to warmer winters and decreasing the frequency of extreme low temperatures, whereas in low-lying coastal plains, mangroves are migrating landward due to sea level rise, as demonstrated for the NE Brazilian coast. Taking into consideration climate change alone, mangroves in most areas will display a positive response. In some areas however, such as low-lying oceanic islands, such as in the Pacific and the Caribbean, and constrained coastlines, such as the SE Brazilian coast, mangroves will most probably not survive.

ISO-Modulating Effects on the East Asian Summer Monsoon Circulation Patterns Associated with Southern Taiwan’s Monsoon Rainfall

AbstractIn this study, the circulation patterns of the summer monsoon associated with monsoon rainfall in southern Taiwan were analyzed and two types of monsoon patterns were defined. The first type was characterized by a broad low pressure area extending northeastward from a low pressure center near southern China to southern Japan. Strong southwesterly flows were observed over the southern flank of the monsoon trough. The second type of monsoon pattern was characterized by a strong westward-extending anticyclone in the area north of Taiwan (including central China, South Korea, and Japan), and a weaker east–west-elongated monsoon trough south of Taiwan, driving the easterly flow to southern Taiwan. The modulating effect of intraseasonal oscillations (ISOs) on these monsoon flow patterns indicates that as ISOs propagate northwestward toward southern China, they create favorable conditions for developing and strengthening southwesterly flows and convection. However, because of the latitudinal limit of northwestward-propagating ISOs, only the edge of the strongest convection over the southern flank of the ISO cyclonic circulation reaches southern Taiwan during the westerly phase. Thus, although the westerly ISO pattern appears to be stronger than the easterly pattern, it brings less rainfall to southern Taiwan. Through the tightening of pressure gradients, the ISO typically generates anomalous cyclones (anticyclones) that can affect the southwesterly and northeasterly flows near its southern (northern) and northern (southern) rims. Therefore, fluctuations in the low-frequency background flow can exert a notable effect on the monsoon rainfall and associated circulation systems near Taiwan.

The distribution and conservation of Gurney’s Pitta Pitta gurneyi in Myanmar

SummaryFollowing a recent assessment of the distribution and habitat use of Gurney’s Pitta in Myanmar (Burma), further extensive surveys were undertaken in 2010, 2011 and 2012. These have extended the species’ known altitudinal limit to between 250 m and 300 m asl and its latitudinal limit to above 12.5°N, around 80 km north of the northernmost historical record, although the species was recorded far less frequently at higher altitudes and latitudes. Birds were recorded in a range of forested habitats, from intact primary forest to secondary and bamboo forest, with no significant difference between major forest types in the likelihood of occurrence. Niche envelope modelling (MaxEnt) suggested a total range size in Myanmar of 3,379 km2, and did not identify any potentially suitable areas in adjacent parts of Thailand. The species’ preference for warmer, wetter areas on flat ground, conditions ideal for growing oil palm and rubber, suggest that its distribution is likely to contract in the near future. The entire range of Gurney’s Pitta in Myanmar falls within the part of the country most suitable for commercial oil palm production, although the projected yields within its range are low to moderate. Field surveys found evidence of rapid recent deforestation and high levels of hunting and trapping in many parts of the region. The species’ range in Myanmar does not overlap with any protected areas. The protection of southern Myanmar’s biodiversity will require substantial investment by foreign conservation interests, sympathetic land-use planning and the strengthening of environment legislation. Protection of extensive tracts of lowland forest within the range of Gurney’s Pitta, particularly the proposed Lenya National Park and the adjacent Ngawun and Htaung Pru Reserve Forests, is urgently needed. Conserving these areas will also protect populations of other globally threatened bird and mammal species.

Spring frost and growing season length co‐control the cold range limits of broad‐leaved trees

AbstractAimThe aim of this study was to test, based on biological theory, which facet of temperature is most closely associated with the elevational and latitudinal low‐temperature limits of seven European broad‐leaved tree species. We compared three temperature‐related potential constraints across three study regions: (1) absolute minimum temperature within 100 years; (2) lowest temperatures during the period of bud‐break; and (3) length and temperature of the growing season.LocationWestern and Eastern Swiss Alps (1165–2160 m a.s.l.) and southern Sweden (57° N–59° N).MethodsIn situ temperature was recorded at the high‐elevation and high‐latitude limits of seven broad‐leaved tree species and correlated with temperatures at the nearest weather stations, in order to reconstruct the temperature regime for the past 50 years. By applying generalized extreme value distribution theory, we estimated the lowest temperatures recurring during the life span of a tree.ResultsAt their high‐elevation limits, five out of the seven tree species experienced winter minimum temperatures considerably warmer than their known maximum freezing resistance in winter. For the bud‐break period, potentially damaging temperatures occurred at both the elevational and the latitudinal limits and for all four species for which phenological data were available. Three out of five species for which a latitudinal replicate was available showed a similar length of growing season at their respective elevational and latitudinal limits. The mean temperature during the growing season was always warmer at a species’ latitudinal limit than at its elevational limit, and hence this variable does not bear general explanatory power for the range limit.Main conclusionsLow‐temperature extremes during bud‐break are the most likely candidates for controlling the elevational and latitudinal limits of broad‐leaved tree species. The absolute minimum temperature in winter and the mean temperature during the growing season are unlikely to constrain the cold limits of these species. Thus, the results call for the use of temperature data (extremes) during key stages of spring phenology when attempting to explain the low‐temperature range limits and to predict the potential range shifts of deciduous tree species.

How accurately can minimum temperatures at the cold limits of tree species be extrapolated from weather station data?

Most plant physiological processes act on micro-geographic scales within meters or less and on temporal scales of minutes or less. Yet, most studies relating species distribution to climate used typical resolutions of kilometers and months at best. Commonly available climate records from weather stations or freely available coarse-resolution geographic climatic layers thus, do not reflect local climatic conditions. In this study we selected sites where eight temperate deciduous tree species are growing at their cold upper elevational and latitudinal limits in the Swiss Alps (from 1165m a.s.l. to 1804m a.s.l.) and in Sweden (from 58°18′N to 59°27′ N). At each site, temperature was recorded for 1–2 years in different conditions: at understorey height (50cm), 2-m above ground, in the top of tree canopies and at 10cm depth in the soil. We compared these biologically meaningful temperatures with the closest weather station data after correction for elevation. The data evidence that in mountain terrain, scaling from weather station data to on-site forest conditions requires month-specific lapse rates of temperatures, separated for means and extremes (e.g. minima). Besides best elevation-correction procedures, monthly absolute minimum temperatures predicted from near weather stations remained 1.4±0.2K (mean±se, 12 sites) cooler than in situ conditions during growing season (2.0±0.2K cooler during the non-growing season). At the time when 2-m air temperature reached its absolute monthly minimum, the top of the tree canopy was found 0.4±0.1K cooler (mean±se, 12 sites) during growing season and 0.9±0.1K during the non-growing season. These systematic deviations of low temperature extremes from those predicted from weather stations close the gap between geographical range limits of species, their physiological limits (e.g. freezing resistance) and meteorological information. The “thermal niche” concept of species range limits needs to account for such deviations of life conditions from meteorological data, should the niche boundaries have a functional meaning rooted in plant biology.

From Corsica to Britain: new outdoor records of Ocnerodrilidae (Annelida: Clitellata) in western Europe.

The ocnerodrilids Eukerria saltensis (Beddard, 1895) and Ocnerodrilus occidentalis Eisen, 1878 are reported for the first time from outdoor localities above 42° N in Europe. The present new records comprise the first ever from England (River Thames, central London) and from France (River Golo, northern Corsica) and the northernmost occurrences in Italy (Liguria and Veneto). The new latitudinal limits and the numerosity of outdoor records suggest that the current environmental and climate changes are substantially enhancing the dispersal and survival possibilities of these worms, even though different transport vectors seem to be involved for the two species.

A reexamination of latitudinal limits of substorm‐produced energetic electron precipitation

AbstractThe primary sources of energetic electron precipitation (EEP) which affect altitudes <100 km (>30 keV) are expected to be from the radiation belts and during substorms. EEP from the radiation belts should be restricted to locations between L = 1.5 and 8, while substorm‐produced EEP is expected to range from L = 4 to 9.5 during quiet geomagnetic conditions. Therefore, one would not expect any significant D region impact due to electron precipitation at geomagnetic latitudes beyond about L = 10. In this study we report on large unexpectedly high‐latitude D region ionization enhancements, detected by an incoherent scatter radar at L ≈ 16, which appear to be caused by electron precipitation from substorms. We go on to reexamine the latitudinal limits of substorm‐produced EEP using data from multiple low‐Earth orbiting spacecraft, and demonstrate that the precipitation stretches many hundreds of kilometers poleward of the previously suggested limits. We find that a typical substorm will produce significant EEP over the International Geomagnetic Reference Field L shell range L = 4.6 ± 0.2–14.5 ± 1.2, peaking at L = 6–7. However, there is significant variability from event to event; in contrast to the median case, the strongest 25% of substorms have significant EEP in the range spanning L = 4.1 ± 0.1–20.7 ± 2.2, while the weakest 25% of substorms have significant EEP in the range spanning L = 5.5 ± 0.1–10.1 ± 0.7. We also examine the occurrence probability of very large substorms, focusing on those events which appear to be able to disable geostationary satellites when they are located near midnight magnetic local time. On average, these large substorms occur approximately one to six times per year, a significant rate, given the potential impact on satellites.

Tracing ancestral biogeography of Sonneratia based on fossil pollen and their probable modern analogues

Extant tropical mangrove Sonneratia is assigned in the monogeneric subfamily of Lythraceae. There are still some debates on the early fossil pollen of Florschuetzia, which is well accepted as ancestral to Sonneratia. This paper re-assesses palynological interpretations on the historical biogeography of the genus, based mainly on the updated fossil pollen records of Paleogene through Quaternary and their probable modern analogues. Florschuetzia was extensively documented from the late Eocene to middle Miocene in palaeotropics around the Tethyan region. According to the geological age of the fossil pollen and their morphological assessments, ancestral Sonneratia migrated from the center of origin in southeastern Asia probably during early Eocene, and radiated and expanded northward to China and Japan, southward to Australia, and westward to east Africa. Until the warmer period of the early middle Miocene (Langhian), Sonneratia had the largest geographical range suggested by abundant fossil pollen from southern mainland China and southwestern Japan, out of latitudinal limit of this extant genus. Quaternary glaciations, especially the Last Glacial Maximum (LGM), played a significant role in shaping the current biogeography of Sonneratia. However unequivocal assignments of early Florschuetzia and the associated variants to the evolved Sonneratia remain an issue due to the lack of intensive morphological comparison from different fossil sites. Thus, we examined the evolutionary trends of the extinct genus Florschuetzia towards Sonneratia on the basis of our synthesis on the updated published data and our recent pollen morphological investigation.

高緯度ハマサンゴを用いた、酸素同位体比(δ18O)とSr/Ca比の骨格成長量依存性の評価

高緯度ハマサンゴを用いた、酸素同位体比(δ18O)とSr/Ca比の骨格成長量依存性の評価

Disentangling the effects of global climate and regional land-use change on the current and future distribution of mangroves in South Africa

The mangrove distribution in South Africa is fragmented and restricted to small forest patches occupying only 16 % of the estuaries within the current range. In this study we used species distribution models to test (1) whether the absence of mangrove forest and its species (Avicennia marina, Bruguiera gymnorrhiza and Rhizophora mucronata) within their current range is driven by climate or by climate combined with human or geomorphic perturbation and (2) how climate change may potentially affect the latitudinal limit of the mangrove forests and its species in South Africa. We used three modelling techniques (generalized linear models, generalized additive models and gradient boosting machines) and a set of three climate-based predictive variables (minimum air temperature of the coldest month, waterbalance and growing-degree days) combined separately with an index of human or geomorphic perturbation. Climate variables for the future projections were derived from two general circulation models driven by two socio-economic scenarios (A2a and B2a). Within the range of the mangrove forest, the fragmented distribution of the mangroves in South Africa was not explained by our set of climate variables alone. The index of human perturbations slightly improved the predictions but the index of geomorphic perturbation did not. Climate change will create climatically suitable sites for the mangrove forest and the two species A. marina and B. gymnorrhiza beyond their current limits, but model outcomes did not agree on the future potential distribution of R. mucronata. We were able to successfully predict range limits and to detect future climatically suitable sites beyond the current limits. Factors controlling mangrove distribution within its range are still to be identified although absences were partly explained by human perturbations.

Do the elevational limits of deciduous tree species match their thermal latitudinal limits?

AbstractAimWe compared the upper limits of 18 deciduous tree species with respect to elevation in Switzerland and latitude in Europe. We hypothesized that species would exhibit the same relative positions along elevation and latitude, which can be expected if species have reached their thermal cold limit along both gradients.LocationEurope and Switzerland.MethodsWe developed a method to identify a least biased estimate of the elevational and latitudinal cold temperature limits of species and for comparing the relative rank positions with respect to these two limits. We applied an algorithm to calculate the elevation of the potential tree line for each point in the gridded landscape of Europe and Switzerland. For each occurrence of each species, the elevation was extracted from digital elevation models. The vertical distance between the elevation of the potential regional climatic tree line and the uppermost species occurrences was calculated and used for comparisons between elevation and latitude.ResultsWe found a strong relationship between the thermal latitudinal and elevational distances of species’ cold limits to the potential tree line, with only marginally significantly different rank positions (P = 0.057) detected along elevational and latitudinal gradients. A first group of nine species showed very similar thermal distances to the potential tree lines along elevation and latitude. Among these species, eight showed a significant decrease in their elevational limit towards high latitudes across mountainous regions of Europe. A second group of seven species occupied a climatic niche closer to the tree line at the edge of their latitudinal range, and only two species did not fill their thermal niche.Main conclusionsOur study provides support for the common concept of a species range–environment equilibrium. Notably, we did not detect a stronger deviation for the filling of thermal niches at latitudinal limits compared with elevational limits, although the former involves a species covering a much greater geographic distance.

Challenges in modelling the abundance of 105 tree species in eastern North America using climate, edaphic, and topographic variables

Improving predictions of the location of suitable environmental conditions for species using species distribution models (SDM) is at the core of biodiversity/climate change research, but modelling species abundance, rather than distribution, is proving particularly challenging. Using data from more than 200,000 forest plots in eastern North America and Random Forest, we evaluated the performance of species abundance models (SAM) in predicting the relative abundance (measured as importance value) of each of 105 tree species in relation to climate, edaphic, and topographic variables. We calculated the coefficient of determination RSAM2 between observed and predicted abundances as a measure of model performance for each species. We also performed multiple linear regressions to explain variation of RSAM2 among species using five biogeographical or spatial attributes of species as explanatory variables. Predictive performances of SAM RSAM2 were generally low, ranging from 0.016 to 0.815 (mean=0.258). Black spruce (Picea mariana) had the best predictive model and Florida maple (Acer barbatum) and American chestnut (Castanea dentata) the worst. Thirty-seven of the 41 best performing species RSAM2⩾0.3 had climate ranked as the best and/or second best predictor. Species with the best performance tended to be those that could reach dominance, showed aggregated distribution of abundance, and/or had high latitudinal limits in the study area. Climate change is likely to affect patterns of dominance in communities by altering patterns of co-occurrences, but for many species that constitute the bulk of tree diversity, predictions based solely on the current distribution of relative abundances may not be reliable enough to inform conservation or management decisions. Predicting tree abundance in a warming climate using SAM remains a challenge, but it is only by reporting performances across a range of climate and statistical models, regions and species, as well as by highlighting model limitations and strengths, that we will improve the reliability of predictions and in turn better inform forest conservation and management.

Coral growth-rate insensitive Sr/Ca as a robust temperature recorder at the extreme latitudinal limits of Porites

Oxygen isotope values of low-growth coral (<5 mm/yr) skeletons may reflect kinetic effects, which is problematic for sea surface temperature (SST) reconstruction. Here, we report a Sr/Ca-based SST reconstruction for a temperate Porites coral collected from Kyushu, Japan, near the northern latitudinal extent of hermatypic corals. Results indicate that Sr/Ca variations in a low-growth coral remain independent from growth rate, in contrast to the oxygen isotope ratios of the same coral.

短期夜间低温胁迫对秋茄幼苗碳氮代谢及其相关酶活性的影响

The frequency,duration and intensity of extreme cold events have been hypothesized to explain the current latitudinal limits of mangrove distribution. At present,Kandelia obovata is the major mangrove species for forestation on the southeast coast of China,whose northern distribution boundary transplanted is in Yueqing county( 28°25'N). Therefore, the incidence of extreme cold events is likely to be a factor limiting mangrove survival ratio. Kandelia obovata seedling grown in a controlled-environment chamber equipped were exposed to two different night temperature regimes:( low temperature treatment)-2℃ and( control) 20℃ for 12 h. During the day,temperature were maintained in both treatments at a minimum of 5 ℃ and a maximum of 25 ℃ for 4 h. Our objective was to investigate the possible physiological mechanisms of Kandelia obovata in responses to the short-term chilling 16 hours. Kandelia obovata seedling were cultivated in the illuminating incubator to study the effects of short-term dark chilling on photosynthetic characteristic,photosynthetic pigment contents,antioxidation system,cell membrane permeability and involved activities of enzymes in carbon and nitrogen metabolism. The results obtained are as follows:( 1) The leaf net photosynthetic rate( Pn),stomatal conductance( Gs) and stomatatal limitation( Ls) of Kandelia obovata were significantly decreased at low temperature 16 h,while leaf intercellular CO 2 concentration was increased.( 2) The contents of chlorophyll,carotenoids,and Chl a / Chl b ratio in leaf had no significantly changes at low temperature less than 8 h,whereas leaf Car / Chl ratio was significantly improved. In addition,photosynthetic pigment contents were decreased at low temperature between 12 h and 16 h.( 3) The leaf total soluble sugars was increased during low temperature 16 h,while sucrose content,sucrose synthase( SS) and sucrose phosphate synthase( SPS) activities were decreased after low temperature 12 h.( 4) The contents of soluble protein and free amino acid and carboxypeptidase activity in leaf were increased during low temperature 16 h,while endopeptidase activity in leaf begun to drop at low temperature 8 h.( 5) During low temperature 16 h,the relative conductivity and malondialdehyde( MDA) content in leaf were increased,while activity of POD was decreased,especially in dark. Also, low temperature both 4 h and 16 h treatments suppressed leaf superoxide dismutase( SOD) activity. These results demonstrate that non-stomatal restriction was cause for reduced Kandelia obovata photosynthesis at low temperature 16 h, which was mainly associated with reduced photosynthetic pigment and depressed antioxidant enzyme activity. Moreover, short-term low night temperature restrained leaf carbon and nitrogen metabolic self-regulation in Kandelia obovata by affecting activities of SS,SPS,endopeptidase and carboxypeptidase.

Enemy release promotes range expansion in a host plant

Climate is considered to be the predominant driver shaping species distributions at macroecological scales, yet the importance of incorporating biotic interactions in predicting future range margins under climate change scenarios is increasingly being recognised. We used translocation studies to investigate how survival and growth patterns of an understory shrub planted at latitudes within its range, at its range limit and beyond its polewards boundary (in areas it may colonise as a result of shifting climate envelopes) are affected by the presence of a primary herbivore. Specifically, we tested the null hypotheses that: (1) biotic interactions do not exert a significant role in limiting survival and growth rates across the limits of a host plant's latitudinal range, and (2) at smaller spatial scales biotic interactions do not exert a significant role in determining survival and growth rates at edge versus interior position within a forest fragment. We found that the understory shrub Macropiper excelsum is able to survive polewards of its current latitudinal limit within the first year after transplant; in fact, growth is higher outside the plant's current natural range than within its present-day distribution. This trend is particularly pronounced in forest core environments and corresponds closely to patterns of reduced herbivory outside the plant's range. The absence of the primary herbivore, Cleora scriptaria, and concomitant reduction in the suppressive effects of herbivory outside of the plant's range appear to be supporting enhanced growth and survival. If host plants are able to successfully track their climatic niche and disperse into novel areas prior to the arrival of their natural predators, it is possible that 'enemy release' may facilitate the establishment of plant species. These findings highlight the importance of considering biotic interactions alongside abiotic variables when predicting future species' ranges under climate change.

Water use characteristics of black mangrove (Avicennia germinans) communities along an ecotone with marsh at a northern geographical limit

ABSTRACTMangroves are expanding into warm temperate‐zone salt marsh communities in several locations globally. Although scientists have discovered that expansion might have modest effects on ecosystem functioning, water use characteristics have not been assessed relative to this transition. We measured early growing season sapflow (Js) and leaf transpiration (Tr) in Avicennia germinans at a latitudinal limit along the northern Gulf of Mexico (Louisiana, United States) under both flooded and drained states and used these data to scale vegetation water use responses in comparison with Spartina alterniflora. We discovered strong convergence when using either Js or Tr for determining individual tree water use, indicating tight connection between transpiration and xylem water movement in small Avicennia trees. When Tr data were combined with leaf area indices for the region with the use of three separate approaches, we determined that Avicennia stands use approximately 1·0–1·3 mm d–1 less water than Spartina marsh. Differences were only significant with the use of two of the three approaches, but are suggestive of net conservation of water as Avicennia expands into Spartina marshes at this location. Average Js for Avicennia trees was not influenced by flooding, but maximum Js was greater when sites were flooded. Avicennia and Spartina closest to open water (shoreline) used more water than interior locations of the same assemblages by an average of 1·3 mm d−1. Lower water use by Avicennia may indicate a greater overall resilience to drought relative to Spartina, such that aperiodic drought may interact with warmer winter temperatures to facilitate expansion of Avicennia in some years. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Vegetation–microclimate feedbacks in woodland–grassland ecotones

AbstractAimClimatic conditions exert a strong control on the geographic distribution of many woodland‐to‐grassland transition zones (or ‘tree lines’). Because woody plants have, in general, a weaker cold tolerance than herbaceous vegetation, their altitudinal or latitudinal limits are strongly controlled by cold sensitivity. While temperature controls on the dynamics of woodland–grassland ecotones are relatively well established, the ability of woody plants to modify their microclimate and to create habitat for seedling establishment and growth may involve a variety of processes that are still not completely understood. Here we investigate feedbacks between vegetation and microclimatic conditions in the proximity to woodland–grassland ecotones.LocationWe concentrate on arctic and alpine tree lines, the transition between mangrove forests and salt marshes in coastal ecosystems, and the shift from shrubland to grassland along temperature gradients in arid landscapes.MethodsWe review the major abiotic and biotic mechanisms underlying the ability of woody plants to alter the nocturnal microclimate by increasing the temperatures they are exposed to.ResultsWe find that in many arctic, alpine, desert and coastal landscapes the presence of trees or shrubs causes nocturnal warming thereby favouring the establishment and survival of woody plants.Main conclusionBecause of this feedback, trees and shrubs may establish in areas that would be otherwise unsuitable for their survival. Thus, in grassland–woodland transition zones both vegetation covers may be (alternative) stable states of the landscape, thereby affecting the way tree lines may migrate in response to regional and global climate change.

Vegetation databases provide a close-up on altitudinal tree species distribution in the Bavarian Alps

Thermal limits of tree species are of paramount interest in monitoring and projecting effects of climate warming. Based on the large phytosociological database BERGWALD, a database of forest inventory plots, and phytosociological tables of vegetation above treeline, tree species occurrence along a regional elevation gradient was assessed separately for tree and regeneration layer individuals. Upper limits in the database were compared to altitudinal limits given in Oberdorfer’s regional flora and to northern latitudinal limits given in worldwide distribution maps. For 26 of 32 tree species, the known distribution limits had to be raised based on plot data, demonstrating the high potential of vegetation databases to deliver ecological information. In most species, regeneration layer occurrences markedly exceeded the altitudinal limit of trees, indicating a potential for rather rapid advances of treelines under climate warming. Regional altitudinal and global latitudinal limits were quite closely related in the majority of tree species. However, several tree species climb to much higher elevation in the Alps than their latitudinal limits suggest. The boreal-subalpine mismatch in cold limits is only partly explained by vicariism and endemism. Sorbus aria, Acer pseudoplatanus, Fagus sylvatica and Taxus baccata are important elements of temperate mountain forests, which do not reach thermally equivalent northern latitudes for unknown reasons.

Temperature variation among mangrove latitudinal range limits worldwide

Mangroves are mainly tropical tree species that occur on either side of the equator and because temperature decreases with increasing latitude, the latitudinal limits of mangroves are expected to be mainly controlled by temperature-related drivers. Here, we hypothesized that the mangrove genera (Avicennia and Rhizophora) have the same limiting temperature at all of their upper latitudinal limits at the global scale. We first derived six parameters from monthly mean sea surface temperature (SST) and air temperature (AT). Furthermore, we investigated whether the variation in these temperature parameters is related (i) to the position of the limit, (ii) to specific temperature requirements of congeneric species and/or (iii) to aridity. All temperature-based parameters derived from AT and SST are highly variable among the upper latitudinal limits of Avicennia and Rhizophora. Hence, we found no common isotherms to characterize the limits of the two mangrove genera, which contradict previous studies. The high temperature variation among limits can be due to partial range filling towards the latitudinal limits. This is supported by the higher warmest month temperatures at the latitudinal limits of the northern hemisphere as compared to the southern hemisphere. However, temperature parameters at limits, with no or less than 250 km of available poleward coast, are not different from other limits, and adult tree height at the limits is not correlated with the temperature-based variables. Mean air temperature is warmer at limits with an arid climate, suggesting mechanisms of compensation towards higher temperatures when Avicennia and Rhizophora have to cope with both aridity and low temperature.

Discovery of a new population of the Critically Endangered frog Insuetophrynus acarpicus Barrio, 1970 (Anura: Cycloramphidae): latitudinal and altitudinal extension in the Valdivian Coastal Range, Southern Chile

A new population of the Critically Endangered anuran species Insuetophrynus acarpicus Barrio, 1970 was discovered during a field survey at Valdivian Coastal Range, Los Ríos Region, Southern Chile. Until now, only three populations have been reported for the species. The new founding described in this paper, which extends the latitudinal limit 21 km to the southwest, and its altitudinal range over 486 m a.s.l, constitutes a very important discovery since the species is considered one of the most threatened species in the country and the world.